Can't unlock tablet

[sarahmartin6084]

I tried unlocking my archos 80 colbalt tablet but whenever i press okay after entering my password my tablet just crashes? i've tried every possible reset method i can find on the internet including methods i found on here, i tried the volume up and power button and that just causes it to crash as well and as far as i can see there is no visible reset hole. Is there any way to get the back off the tablet and take a battery out or is my tablet ruined? any help will be much appreciated, thanks. x